Process and devices for the production of blanks, cores, and moulds for casting purposes



Apnl 26, 1960 F. HANSBERG 2,933,785

PROCESS AND DEVICES FOR THE PRODUCTION OF BLANKS, CORES AND MOULDS FORCASTING PURPOSES Filed March 20, 1957 7 Sheets-Sheet 1 INVENIUP FQ/rZ///9A/J8R G 7 Sheets-Sheet 2 April 26, 1960 F. HANSBERG PROCESS ANDDEVICES'FOR THE PRODUCTION OF BLANKS, CORES AND MOULDS FOR CASTINGPURPOSES Filed March 20, 1957 Hllil Apnl 26, 1960 F. HANSBERG 2,

PROCESS AND DEVICES FOR THE PRODUCTION OF BLANKS, CORES AND MOULDS FORCASTING PURPOSES Filed March 20. 1957 7 Sheets-Sheet 3 Hrrokmsfi April26, 1960 F. HANSBERG 2,933,785

PROCESS AND DEVICES FOR THE'PRODUCTION 0F BLANKS, CORES AND MOULDS FORCASTING PURPOSES Filed March 20, 1957 7 Sheets-Sheet 4 FIG. 6

F767 l/ld a 81 HOW We Quad firromvsrs April 26, 1960 F. HANSBERG CORES 7Sheets-Sheet 5 PROCESS AND DEVICES FOR THE PRODUCTION OF BLANKS ANDMOULDS FOR CASTING PURPOSES Filed March 20, 1957 gzy /z l v v mm ::ti.

r g llllll fiwz-wrop FR/rz A /weave 2,933,785 CORES April 26, 1960 F.HANSBERG PROCESS AND DEVICES FOR THE. PRODUCTION OF BLANKS AND MOULDSFOR CASTING PURPOSES 7 Sheets-Sheet 6 Filed March 20, 1957 HH ll!Hrromws/s April 25, 1960 F. HANSBERG 2,933,785

PROCESS AND DEVICES FOR THE. PRODUCTION OF BLANKS, CORES AND MOULDS FORCASTING PURPOSES Filed March 20, 1957 i 7 Sheets-Sheet 7 F76. If

PROCESS AND DEVICES FOR THE PRODUCTION OF BLANKS, CORES, AND MOULDS FORCAST- ING PURPOSES Fritz Hansberg, Modena, Italy Application March 20,1957, Serial No. 647,325

Claims priority, application Germany March 23, 1956 25 Claims. (Cl. 22-10,)

This invention relates to a process and 'a moulding machine of use forinstance in foundries where core sand or moulding sand or othershapeable substance has to be charged into a core box or moulding box.The invention also relates to a box therefor and can be used in otherfields where similar problems arise, for instance, for the production ofshaped members made up of sands andv of air and sand, and sand shootingmachines in which the moulding sand is simply displaced by impact intothe box to be charged without any special eddying and mixing. Thecharacteristic features are explained in the introduction to the UnitedStates Patent No. 2,793,409, Serial No. 456,205, filed September 15,1954.

In one very simple method of mixing, compressed air is used to create asuction acting upon the moulding sand at the exit from a sand chamber,and the sand, mixed with the compressed air in a kind of suspension, iscarried into the core box or moulding box. When the compressed air isintroduced into the sand chamber, machines operating on the blowingprinciple produce a very intimate mixing of the sand in the chamber withair. By this means, the sand is loosened by fully pneumatic means beforebeing blown from the sandchamber, each grain of sand being surrounded bycompressed air and only then being blown into the core box or mouldingbox after the fashion of a suspension. As a rule, an agitator foragitating the supply of sand is provided in the sand chamber to improvethe mixing of the supply of sand to be loosened with the mixing airwhich is introduced into the supply of sand downwardly and, as a rule,laterally too. It is also known to combine these several separate stepsin such manner thatcompressed air is also used to produce adownward-acting pressure upon a shapeable substance which is disposed ina closed pressure vessel and which may or may not be agitated therein,compressed air also being used to apply suction to the said substance atthe exit thereof from the vessel. To this end, at least one deliverynozzle of the pressure vessel is formed as an injector, for instance, byproviding in the vessel an injector-like casing, which is rigidlysecured to the base of the vessel and to which compressed air is ciple,the moulding sand being urged into the core box or moulding box to becharged, abruptly as a compactv mass without any special mixing withair. The necessary acceleration is imparted to the moulding sand byresilient pressure, for instance, by compressed air acting, after thefashion of a resilient piston, upon one end surface of the column ofsand and urging the same abruptly through a nozzle into the core box ormoulding box. The compressed air enters from one side and acts upon theend face of the sand column, and the sand issues on the other sidethrough the nozzle in the form of a compact stream into the box which iswholly or partly charged depending upon the quantity of sand to-whichpressure has been applied. The considerable acceleration imparted by theair pressure to the sand issuing from the nozzle enables the sand tofill all the interstices of the core box or moulding box completely as acompact and cohesive substance.

' The invention provides a third process and a third category ofmachines not involving a positive application of artificial force to thesupply of sand, the charging of the core box being effected through theagency of an abruptly created static pressure difference between thesupply of sand and the inside of the core box. This has the specialadvantage that the supply of sand need not be charged into apressure-tightclosable container, but can be contained in a simple sheetmetal trough orthe like which is open at the top and which can berefilled in any desired manner without the need of a charging slide orother devices such as are essential for the sand chambers of machinesoperating on the blowing or shooting principle. The need to raise andlower a machine table before and after the charging of the box iseliminated; on the contrary, the novel machine can simply be formed as atable support. Thereis no wear on core boxes such as is disadvantageouswith the dynamic processes and more particularly with a blowing machinehaving an air-supply injector nozzle. Furthermore since there is a largedegree of independence from the need to carefully arrange the flow ofsand into the box to be charged, complicated cores can be produced.

The process according to the invention for producing shaped objects froma shapeable. substance, more particularly for the production of foundrycores and foundry moulds, which might be called the vacuum mouldingprocess, is distinguished in that a compactsupply of sand is initiallyplacedimmediately before the one or more charging apertures of the corebox or moulding box, whereafter a negative pressure is produced veryrapidly and abruptly in the box interior to be charged, the pressuredrop being so great that enough of the compact supply of sand to chargethe box penetrates correspondingly rapidly and abruptly, into the boxinterior. which is thus filled completely. 7 v

Expediently, the abrupt pressure drop in 'the box interior is producedat one or more stations therein which are opposite the sand entry. Inorder that eventhe furthest regions of the box interior may be filledcompactlywith the moulding sand or the like, the pressure drop isexpediently produced also or only by one or more station's inside thebox, such station or stations being furthest from the sand entry inrespect of the distance which the sand has to travel inside the box whenthe box is charged. To ensure that cut-back parts of the box interiorare filled compactly, the pressure drop is produced also or only fromsuch cut-back regions.

The core-box or moulding box according to the invention and serving forthe carrying out of the vacuum moulding process according to theinvention, which box can be called a vacuum box, is first distinguishedin that it has suction channels for theproduction 'ofya negativepressure or vacuum in the interior to be charged.

Conveniently, in accordance with the process, the inner apertures of thesaid suction channels are disposed at those regions of the box interiorwhich are opposite the sand entry .of the box and also or only at thoseregions of the box interior which are furthest from the sand entry inrespect to the distance which the sand has to travel in the box. If thebox interior has cut-back regions, inner apertures of the box suctionchannels are provided also or .only at the cut-back regions.

Advantageously, the negative pressure channels which serve to producethevacuum in the box interior and which are disposed in the box wallsextend to one or more central suction stations of the box, the centralsuction stations conveniently being dished recesses in the 'outer wallsof the box. Where the vacuum box is to be fitted to a table plate or thelike having'suction nozzles for the production of the negative pressurein its interior, a particularly'good suction efl'ect is produced ifajse'aling means, for instance, of. rubber or other sealing resilientmaterial, is provided around the possibly dish-shaped suction stationsin the outer walls of the box.

-The suction channelscan simply be'drilled in the walls of the box andtheir inner apertures provided with conventional fine-slotted nozzlesotherwise known as evacuating nozzles. If the various suction stationsinside the box cannot be connected to the dish-shaped outer suctionstation by rectilinear direct bores, the required connection can beeffected through the agency of trans- Verse channels blanked off at theinoperative end.

The moulding machine according to the invention for carrying the vacuumprocess according to the invention finto effect, which can be called avacuum moulding machine, is initially distinguished by a suction nozzlefor producing a negative pressure in the interior of the core box ormoulding box to be charged, and also by an open sand supply container,that is, a container subject to atmospheric pressure, having oneorpossibly more sand outlet nozzles for the arrangement of a .compactsupply of sand immediately before'the one or more charging apertures ofthe core box or moulding box to be charged.

The sand supply container can consist merely of a thin .walled,funnel-shaped or trough-like container made of .sheet metal or the like,the base possibly being thicker and being formed with one or more sandoutlet nozzles.

While the process and apparatus according to the invention allow ofhorizontal and inclined operation, it is very advantageous if thecharging operation is performed vertically and downwards. To this end,the open sand :container is disposed above the box to be. charged and isso mounted as to be pivotable laterally and/or adjust- "able in height.In one advantageous embodiment, the mounting of the open containercomprises a hollow column in which a piston is axially displaceable, thetop piston rod end carrying the open container and therefore .beingadapted to project out of the top of the bearing column. The operationof the piston, and therefore the adjustment of the height of the sandcontainer for engagement with the box to be charged and for subsequentraising, can be effected hydraulically but is conveniently performedpneumatically by compressed air, which is always available in foundriesand is used generally as a driving medium. For a coarse adjustment tothe height of the core box, the hollow bearing column can be mounted forvertical displacement on the machine frame, the said column having, forsuch adjustment, an externally screw-threaded spindle and a handwheel. Aspecial construction of the sand container relates to the use of one -ormore slotted nozzle ends of resilient material in one or more of thesand delivery nozzles of the sand container. Preferably, such a nozzleend has the shape of a hollow cone which is retained at the top in thesand delivery nozzle by a retaining collar and which can be made ofrubber. The advantage of a nozzle end of the kind specified is thatthere is no need to adapt the-size of th sand delivery nozzle to thecore sand used, since the nozzle end prevents very fine-grain drymixtures of sand and synthetic resin, such as are used, for instance,for the Croning process, from running out unwantedly. By virtue of theslotted arrangement, the nozzle end can open after the fashion ofresilient jaws for the moulding sand to flow through into the box to becharged. 7

To facilitate the penetration of the compact sand from the sandcontainer into the box to be charged, an electric or pneumatic vibrationmotor known per se can be provided on the container wall, such motorbeing operated at least during the charging of the box.

In a particularly advantageous embodiment of the vacuum moulding machineaccording to the invention, the suction nozzle for producing thenegative pressure in the interior of the core box to be charged isdisposed in the machine table upon which the core box merely needs tobeplaced and, after positioningof .the sand container, charged. Thesuction nozzle can consist of a conventional slotted nozzle of the kindused for removing air from core boxes. If the cores or core boxes arerelatively large in extent, more than one suction nozzle can be providedin the machine table, the nozzles being sealed off by plugs or cockswhen not in use.

Expediently, the vacuum pump serving to produce the negative pressure inthe boxinterior is enclosed in the frame of the vacuum moulding machine.In one advantageous embodiment of the invention, the frame of the vacuummoulding machine is itself formed as a vacuum pump, for instance, if themachine frame forms one or more cylinders in which, for instance, adouble piston operates to produce the-vacuum. In one very advantageousembodiment of the vacuum moulding machine according to the invention,the base of the machine table is formed as a vacuum pump. Preferably,the said base comprises two cylinders which are disposed one uponanother and. in which a double piston moves vertically to produce thevacuum. Expediently, the bottom piston and the corresponding bottomcylinder are larger in diameter than the top piston and correspondingtop cylinder, with the result that the vacuum is produced more abruptlyand impactwise. Intermediate the two cylinders disposed one on top ofanother there can be provided a separate intermediate plate which canhave the channels for the supply and delivery of the operatingcompressed air to and from the cylinders and which can also havequick-acting 'air valves.

A suitable form of quick-acting valve for the purpose air is admitted,that its end face, which has sealing means, is pressed against asmaller-diameter valve seating in the outlet channel. The control pistonreleases a lateral air admission channel comprising a non-return valve,for instance, in needle form, which non-return valve, when thecompressed air ceases to be applied, restricts the flow of air returninginto the lateral channel to such an extent that the air pressure uponthe two sides of the control piston is different and the excess pressureacting upon the sealing end face of the control piston lifts the sameoff the seating, with the result that the lateral channel is sealed bythe wall of the control piston and one or more air outlet apertures arereleased. The supply of compressed air to the quick-acting compressedair valves of the cylinders can be governed by a central control valvewhich can also, if required, serve. to actuate the piston associatedwith adjustment of the height of the sand supply container. 1 1Conveniently, to protect the vacuum pump against the entry of fineparticles of sand, the suction pipe extending from the core box ormoulding box to the vacuum pump inlet'comprises an air filter and/or airwasher. In the embodiment having a table nozzle, the machine table platecan have suction channels extending from the table D 2 0 e airfilterand/or air washer and thenceto '5 the suction 'chambe'r of "thetop cylinder of the machine table base. Preferably, the machine tableplate is formed 'with at least one other outlet channel extending fromthe suction chamber of the top cylinder to a non-return valve which is,for instance, spring-loaded and which, after the charging of the box,serves to re-eject air sucked out of the box interior. Conveniently, anumber of such airejecting non-return valves can be distributed aroundthe bottom of the machine table. If an air filter is used, this can berod-shaped and so introduced laterally into the machine table plate thatthe actual filter element extends into the suction channel in the tableplate and filters the air sucked through. Like the air ejection valves,the air washer can be borne by the machine table plate.

It has been found that the filtering of the air evacuated abruptly bythe vacuum pump from the core box or moulding box to be charged can beperformed more simply and with considerably reduced suction losses ifthe air filter is disposed directly in the machine table between thetable suction nozzle and the inlet side of the vacuum pump, the airfilter taking in this case the form of a wide-surface filter layerpreferably of the same diameter as the suction piston of the vacuumpump.

The filter layer can consist,-for instance, of granular metal swarf orof, for instance, granular plastic or any other suitable filtermaterial. To facilitate air filter'replacement, it is very advantageousif the air filter takes the form of a finely perforated, box-like filtercapsule releasably introduced into the machine table and charged withthe filter material. A preferably plate-like ceramic filter memberreleasably introduced into the machine table can also serve as thefilter layer.

Conveniently, the machine table plate is formed as a number of parts,one of the component plates being formed with a recess to receive thepreferably capsulelike or plate-like filter layer. Conveniently, wherethe same is disposed in the bottom plate, it is retained by means of thetop plate which has the suction nozzles. More advantageously, however,the filter layer is disposed in the top plate and retained through theagency of 'a cover plate fitted with the suction nozzles, for then theunderplate can have a substantially plane surface and the filter layercan be replaced more readily, merely by releasing the cover plate.

Since the moulding machine is particularly suited for carrying outthemould mask process, where the moulding sand is mixed with liquid orpowdered synthetic resin and the box serving to produce the mouldingmasks must be 'heated, the top plate is conveniently formed as a hollowchamber through which a cooling liquid can fiow, so that the filterlayer in the machine table plate and the associated suction nozzles canbe cooled and are not caked bythe. synthetic resin. Sealing means areprovided between the top and bottom plates in the boundary gap; theysurround the suction channels or the filter layer and protect them fromthe cooling liquid.

Preferred embodiments of the vacuum moulding machine according to theinvention and of the vacuum box according to the invention arediagrammatically illustrated,'with details, in the accompany drawings inwhich:

Figure 1 is a side elevation of the vacuum moulding machine, the sandcontainer lifting device and the fitted vacuum box being shown insection;

Figure 2 is a front elevation, in vertical section, of the vacuummoulding machine with the vacuum box of Figure 1 fitted;

Figure 3 is a view in section on an enlarged scale of the nozzle end ofthesand supply container shown in Fig- Hire "Figure. 4 illustrates, invertical section and on an enlarged scale,'another embodiment of thenozzle plate of the sand container and of a vacuum box;

Figure 5 is a view, in vertical section and on an en larged scale, ofthe air-ejecting non-return valve shown in Figure 2;

entrees Figure 6 is a view, invertical'sectic'm andori *an' en.- largedscale, of the table suction nozzle shown in Figure 2;

Figure 7 is a view, in vertical section and on an enlarged scale, of oneof the two identical quick-acting compressed air valves shown in Figure2;

Figure 8 is a view, in vertical section and on an enlarged scale,through the air washer shown in Figure 2;

Figure 9 corresponds to the top of the moulding machine illustrated invertical section in Figure 2, but with the difference that, instead ofthe lateral air'washer, a filter capsule is disposed in the machinetable;

Figure 10 shows the filter capsule of Figure 9 separately and to anenlarged scale, and

Figure 11 is a constructional variant of Figure 9 and shows how thefilter layer can be arranged in the bottom plate of the machine table.

Referring to Figures 1 and 2, the vacuum moulding machine comprises apedestal-like frame '1 which bears a machine table 2 at the top and hasat the rear a swing arm 3 for holding a sand supply container 4. Themounting of the sand supply container 4 comprises a hollow bearingcolumn 5 rigidly secured in the swing arm} and having, for verticalheight adjustment, 'an externally screwthreaded spindle and, restingupon the swing arm 3, a'spindle hand wheel 6. A piston 7 can movevertically in the hollow inside of the column 5 and can be. controlledpneumatically or hydraulically by way of a control supply pipe 8. Thefree top piston rod end 9 bears on an arm 10 a relatively thickbaseplate 11 of the container 4. In the example illustrated, only onesand outlet nozzle 12 is provided in the baseplate 11 and receives aresilient, slotted nozzle end 13. The container 4, which is a truncatedconical funnel in the example illustrated, is made of thin sheet metaland is open at the top. Disposed on the wall of the container 4 is avibration motor 14 which is operated at least during the filling of thevacuum box 15 fitted to the machine table 2 and which facilitates thepassage of the compact supply of sand 16 from the container 4 throughthe nozzle 12, 13 into the interior 17 of the vacuum box 15. The heightH of the core box can be adjusted by means of the handwheel 6, while bymeans of the hollow bearing column 5 and the piston 7 therein, the,container 4 can be raised and lowered through the reduced distance h orswung out laterally.

Referring to Figure 2, the base 1 is formed as a vac} uum pumpand tothis end comprises two cylinders 18 and 19 which are disposed one on topof another and in which a double piston 20 moves vertically to produce avacuum. The bottom cylinder 18 is larger in diameter than the topcylinder 19 'andbears the latter with the interposition of anintermediate plate 21. Corresponding: ly, the bottom piston 22 has alarger operative area than the top piston 23. Formed in the plate 21 areducts 24 and 25; the duct 24 serves tosupply and remove com pressed airto and from the bottom cylinder 18 and the duct 25 serves to supply andremove compressed air to and from the top cylinder 19. Also'fitted tothe plate 21 are two quick-acting compressed air valves 26 and 27connected, by way of air lines 28 and 29, to a central control valve 30to which compressed air is supplied through a supply pipe 31. The topcylinder 19 bears the machine table plate 32 of the machine table" 2.The machine table 2 has, in the embodiment illustrated, only one suctionnozzle 33 over which the vacuum box 15 tobe charged is placed. A suctionpipe 34 extends from: the nozzle 33 to a'disc-shaped channel 35 andthence, by way of a suction duct 36, to an air filter introducedlaterally into the machinetable 'plate'32, and thence toan air washer 38borne'by'the plate 32, and thence, by

way of another suction duct 39, to the suction chamber 40 of the topcylinder 19. The plate 32 also has outlet ducts 41 which are disposed inradial direction and which. extend from the suction chamber of the topcylinder 19 to aireiecting nonreturn valves 42-distributed around thebottom of the plate 32. The disc-shaped outlet Channel 35 is separatedfrom the suction chamber 40 by a sealed disc 43.

Referring now to Figure 3, the sand outlet nozzle 12 in the baseplate 11of the container 4 is provided with a nozzle end 13 which consists ofresilient material and is in the form of a hollow cone having at itsupper and widened end a retaining collar 44 serving for the mounting ofthe nozzle end 13 in the nozzle 12, in which it is retained by a snapring 45. By virtue of one or more vertical slots 46 which extend fromthe cone apex to the collar 44, the nozzle end 13 can open after thefashion saute ends 13 of rubber.

In the vacuum box illustrated in Figure 2; filter-like apertures 48 ofthe box suction ducts 49 are contrived .in the base of the box interior17 only opposite the sand entry 47. The ducts 49 extend to a centralsuction station 50 which comprises a dish-shaped recess in the box outerwall and is disposed above the suction nozzle 33 of the machine table 2.The ducts 49 act as negative pressure ducts for the production of thevacuum in the box interior 17. On the other hand, in the vacuum box 15illustrated in Figure 4, internal filter-like slotted apertures 51 arealso provided at undercut regions 52 of the box interior 17. Alsoprovided are inner filter apertures 53 which: are furthest from the boxentry 47 or sand outlet nozzle 12 in respect of the distance which thesand has to travel from the said entry 47 in the interior 17. Thelateral negative pressure apertures 51 and 54 communicate, by way ofnegative pressure ducts 49a extending transversely in the box wall, withthe dish-shaped central suction station 50, their inoperative ends beingblanked off by plugs 55. To produce a very powerful suction and chargingeffect, the topand bottom of the vacuum box illustrated in Figure 4 areprovided with sealing means 56 around the sand entry 47 and thedish-shaped suction recess 50, the sealing means consisting in this caseof rubber.

Referring to Figure 5. the air-ejecting valve 42 of the top cylinder 19comprises a casing which has a number of circumferentially spaced outletapertures 57 and which is screwed to the bottom of the plate 32. Mountedin the casing is a tappet valve 58 acted upon by a closure spring 59which urges the resilient valve head 60 against the seating 61 of theair outlet duct 41. When the top piston 23 rises, the air expelledthrough the duct 41 lifts the valve head 60 from the seating 61 andflows through the apertures 57 to atmosphere.

The table nozzle or suction nozzle 33 shown in Figure 6 comprises aslotted nozzle screwed into the table 2 by means of a screwthreaded tube62. Disposed below the nozzle 33 is a close-meshed filter 63 whichfilters the air sucked from the box 15 before such air enters thesuction pipe 34 of the plate 32. The nozzle 33 can be screwed outtogether with the tube 62 and replaced by a screwthread plug or a setscrew, for instance, if a number of such nozzles 33 are provided in thetable 2 and some of them' are not required. Referring to Figure-7, thequick-acting compressed air valve 26 and 27 serves to supply and removethe working compressed air toand from the cylinders 18 and 19respectively. Thevalve 26.and 27 has a screwthreaded eonneetion 64, thefree end of which is screwed into the aperture-of the ducts 24andrespectively in the interirlediate plate.21. 'A control piston 66 can befreely displaced horizoritallyin the'valve casing 65. ,The piston66Ihas. 'on its end'face'6'l'fsealing means 68' which, when thepis'toii-66 .is in'thef left-hand end position, bears ggar s iavawe 'seating'i69lof air outlet'ehannel .70,

The seating 69 is smaller in diameter than the piston 66, so that theleft-hand pressure surface of the piston 66 is smaller than theright-hand pressure surface thereof when the piston 66 has its sealingmeans 68 urged against the seating 69. In this position the piston walluncovers the aperture 71 of a lateral air intake channel 72 throughwhich the compressed air supplied by way of the air connection 73 canflow. Such air lifts, in the inner outlet aperture of the lateralchannel 72, a releasably fitted conical pin 74 which acts under its ownweight as a nonreturn valve. When the piston 66 is in its right-hand endposition, its wall seals off the entry aperture 71 of the lateralchannel 72, while its end face 69, which is then raised clear of thevalve seating 69, opens a passage from the air exit channel to a numberof circumferentially spaced air exit apertures 75 arrangedin stellateform. e The air cleaner illustrated in Figure 8 comprises an air filter37, which is introduced laterally into the plate 32, and an air washer38 which is screwed on to the bottom of the plate 32. The filter 37 isfitted to a rodlike bearer 76 and extends into the widened end of thesuction duct 36 so that the air sucked through the duct 35 must passthrough the filter 37, whence it passes through another close-meshfilter '78 and through circumferentially spaced apertures 79 in themember 76 to the air washer 38. The entry tube 80 of the air washer 38is screwed into the bottom of the plate 32 and extends deeply into aliquid vessel 81 screwed on to the bottom of the plate 32 and forces theair to pass through the washing liquid which, in the exampleillustrated, is oil. The compressed air which rises in the vessel 81passes through two close-mesh filters 82, reaches the return suctionduct 39 and passes therethrough to the suction chamber 40 of the vacuumpump. In the embodiment illustrated in Figure 9, the top plate 2 isformed with a recess 83 on its bottom surface and the filter layer 84 isintroduced into the recess 83, the filter layer 84 taking the form ofthe box-like perforated filter capsule 85 shown to an enlarged scale inFigure 10. The capsule 85 is retained at the top by means of a coverdisc 86 which in this embodiment contains the suction nozzles 33 andwhich is formed with a disc-like distributing duct 87 on its bottomsurface. A matching disc-like distributing duct 88 is formed below thefilter capsule 85 in the plate 32, and three ducts 89 extend from theduct 88 to the suction chamber 40 of the cylin= der 19. The top plate 2is formed as a hollow chamber so that cooling liquid supplied andremoved by way of the connection 90 can flow through the top plate 2. Anannular packing 91 which screens the filter layer 84 from the coolingliquid is provided around the filter layer 84 131;: the gap between thetop plate 2 and the bottom plate In the machine according to Fig. 11,the lower plate 32 is formed with a recess 83 to receive the filterlayer 84 which is encased in the box-like perforated filter capsule 85retained by cover disc 86. The suction nozzles 33 are disposed insuction ducts 92 formed in upper table plate 2. This table plate alsoincludes channels and the ducts 92 are sealed by sealing rings 91against thecoolant flowing through the machine.

The vacuum moulding machine shown in Figures 1 to 8 operates as follows:l The core box 15 to be charged is so fitted to the machine table 2 thatits dish-like central suction station 50 is disposed above the suctionnozzle 33 of the machine table 2. The sand container 4, which may havebeen swung out laterally and which may be in the raised position; isbrought over the charging aperture 47 of thecore box'15 and lowered onto said aperture by removing air from ,thepiston supply pipe 8. When thecontrol valve lever 30 is moved intothe position I, compressed airissupplied from the air line 31 byway of thelipej 29 '9 -'to thequick-acting air valve 27, moves the =c'ontrol piston '66 into itsleft-hand end position and thus seals the air exit duct 70. By way ofthe lateral channel 72, the compressed air, lifting the non-return valve74, passes through the tubular connection 64 and the duct 25 in theintermediate plate into the top cylinder 19 below the top piston 23which thus moves into its uppermost position and, in so doing, expels toatmosphere any air in the suction chamber 40 by Way of the outlet duct41 and the outlet perforations 57 of the air-ejecting non-return valve42.

When the lever of-the control valve 30 is pivoted into its position IIso that the air line 29 has the air removed from it, the compressed airin the cylinder 19 reacts upon the control piston 66. The needle valve74 restricts the pressure in the lateral duct 72 to such an extent thatthe compressed air acting upon the piston end face 67 in the air outletduct 70 abruptly urges the control piston 66 into its right-hand endposition, with simultaneous sealing of the entry aperture 71 of thelateral duct 72. Hence the compressed air in the cylinder 19 can flowwithout restriction to atmosphere by way of the air outlet aperture 75.Simultaneously, compressed air is supplied, by way of the centralcontrol valve 30, from the air line 31 through the air line 28 to thequick-acting air valve 26 of the bottom cylinder 18 and urges the bottompiston 22 into its bottom end position. Since the operative area of thebottom piston 22 is greater than the operative area of the top piston23, the double piston 20 is moved downwards abruptly.

As the top piston 23 descends, a vacuum is produced in the suctionchamber 40 and acts, by way of the suction duct 39, air washer 38, airfilter 37, and suction ducts 34 to 36, upon the core box 15 to becharged. As a result, the air in the interior 17 of-the core box 15 isremoved through the nozzle apertures 48, box suction duct 49, thedish-shaped central suction station 50, and the suction nozzle 33 of themachine table 2. It is filtered on the way to the vacuum piston 23 inthe air filter 37 and freed from the last particles of sand in the airwasher 38.

As a result of the production of an abrupt and considerable pressure,drop in the box interior 17, the co'mpact sand 16, under the eifect ofthe static pressure difference between the sand 16 and the box interior17, urges apart the slotted resilient nozzle end 1'3, rushes out of thecontainer 4 through the outlet nozzle 12 and penetrates into the boxinterior 17 which is thus charged completely and compactly.

The piston 7 is again supplied with pressure medium by way of the pipe 8and the container 4 is again raised by the distance h and, if required,swung out to one side. The charged box 15 can then be-removed from thernachine table 2 and released from the finished core,

an operation which can, if required, be performed on the machine table2.

- The vacuum moulding machine further charging operation.

The vacuum moulding machine illustrated in Figures 9 to 11 operates onthe same basic principle as the machine illustrated in Figures 1 to 8,as follows:

The core box 15 to be charged is sofitted to the machine table 2, 32that its dish-shaped central suction station 50 is disposed above thesuction nozzles 33. The sand supply container 4, which may have beenswung out to one side and which maybe in the raised-position, is broughtover the charging aperture 47 of the core box 15 and lowered on to saidaperture. By appropriate operis then ready for a ation of the controlvalve (not shown), the top piston 23 isdriven into its uppermostposition and,. in so doing, expels to atmosphere any air in thesuct-ionchamber by W y of the outlet duct 41 and outlet perforations in theair-ejecting non-return valve 42. g vI f the control valve {not shown)is again operated,'t-h'e top piston 23 is driven downwards impactwiseinto its bottom en'dpositiomwith the result that 'a v'ac'uum is 15rdduced in the suction chamber 40 and extends, by way of the suction ducts89, wide-surface filter layer 84 and suction nozzles 33, to the box 15to be charged. As a result, the air in the interior 17 of the box 15 isremoved, by way of the nozzle apertures 48, box suction duct 49, thedish-shaped central suction station 50, and the suction nozzle 33 of themachine table 2. It is filtered on the way to the vacuum piston 23 inthe wide-surface filter layer 84 and thus freed from sand particles. Asa result of the considerable and abrupt pressure drop in the boxinterior 17, the compact sand 16, under the effect of the staticpressure difiference between the sand 16 and the box interior 17, widensthe slotted resilient nozzle end 13, rushes from the sand container 4through the sand outlet nozzle 12, penetrates impactwise into the boxinterior 17 which is thus charged completely and compactly.

If the sand container 4 is then raised again and, if'required, swungaside, the charged box 15 can be removed from the machine table 2 andreleased from the finished core, an operation which, can, if required,be performed 'on the machine table 2.

The vacuum moulding machine is then ready for a further chargingoperation.

I claim:

l. A machine for producing casting blanks, casting cores and castingmolds, comprising a support structure for supporting a box to be chargedwith molding sand and quick acting vacuum pump means including a suctionchamber of comparatively large reception volume for abruptly creating acomparatively high vacuum in the interior of said box, said supportstructure forming at least one cylinder constituting said suctionchamber of comparatively large reception volume, a piston displaceablein said cylinder to produce the vacuum, and a suction nozzle connectedto said suction chamber and communicating with said box supported onsaid support struc- 'ture.

2. A machine for producing casting blanks, casting cores and castingmolds, comprising a support structure for supporting a box to be chargedwith molding sand and quick acting vacuum pump means including a suctionchamber of comparatively large reception volume for abruptly creating acomparatively high vacuum in the interior of said box, said supportstructure forming two cylinders in tandem, one of said cylindersconstituting said suction chamber of comparatively large receptionvolume, a twin piston displaceable in said cylinders to produce thevacuum, and a suction nozzle connected to said suction chamber andcommunicating with said box supported on said support structure.

3. Machine according to claim 2, wherein said two cylinders in tandemare disposed upright and form a machine table base including a machinetable for placing a box thereupon with at least one suction nozzleformed therein, said nozzle being connected to said suction chamher andcommunicating with the box supported on said table.

' 4. Machine according to claim 3 characterized in that the bottompiston and cylinder are of larger diameter than the top piston andcylinder.

- 5. A machine for producing casting blanks, casting cores and castingmolds, comprising a support structure for supporting a box to be chargedwith molding sandand quick acting vacuum pump means including a suctionchamber of comparatively large reception volume for abruptly creating acomparatively high vacuum in the interior of said box, said supportstructure forming two cylinders in tandem, one of said cylindersconstituting said suction chamber of comparatively large receptionvolume, a twin piston displaceable in said cylinders to produce thevacuum, and a suction nozzle connected to said suction chamber andcommunicating with said box supported on said support structure, aconduit for supplying pressure air and discharging the air from saidcylinders to effect displacement of the twin piston, and quick actingair valves to control the fiow of air through said conduit means.

6. A machine for producing casting blanks, casting cores and castingmolds, comprising a support structure for supporting a box to be chargedwith molding sand, said sup port structure forming quick acting vacuumpump means including a suction chamber of comparatively large receptionvolume, a nozzle connected to said suction chamber, said suction nozzlecommunicating with a box supported on said support structure forproducing an abrupt pressure drop in said box upon activation of saidpump means, said vacuum pump means including two cylinders formed insaid support structure, a piston slidable in each of said cylinders toproduce said pressure drop by displacement of the pistons, said pistonsbeing coupled for joint movement, a conduit means for supplying pressureair to and discharging from saidcylinders to effect displacement of thepistons therein, and quick acting air valves to control the flow of airthrough said conduit means, said conduit means including an air inletconduit and an air outlet conduit, said quick acting air valves eachincluding a housing, a control piston having sealing means on one of itsfaces and slidable in said housing, said piston being movable bycompressed air into a position in which said piston face presses againsta valve of smaller diameter seating in the air outlet conduit, saidmovement of the control piston uncovering the air inlet conduitlaterally issuing into the housing, said inlet conduit including anon-return valve which upon discontinuation of the flow of pressure airlimits the fiow of air into the lateral conduit to such an extent thatthe resultant excess pressure acting upon the face of the control pistonhaving said sealing means lifts said face off its seating whereby saidlateral conduit is sealed and at least one air outlet aperture isuncovered.

7. In a machine for producing casting blanks, casting cores and castingmolds by charging of a box with molding sand, a machine base including atable plate for placing thereon the box to be charged with sand, saidbase being in the form of a quick acting pump having a suction chamberof comparatively large reception volume, said pump comprising twocylinders disposed upright in tandem and a twin piston reciprocatory insaid cylinders, one of said cylinders constituting said suction chamber,a suction nozzle included in said table plate for'coacting with the boxplaced thereupon, a suction pipe connecting said nozzle with saidsuction chamber to effect an abrupt pressure drop in the box in responseto a displacement of said pistons in a direction for creating a vacuumin said chamber, and an air filter means included in said suction pipe.

8. A machine for producing casting blanks, casting cores and castingmolds, said machine comprising a holder for molding sand, said holderbeing open at the top to the atmosphere and having a discharge opening;a suction chamber with high air capacity and comparatively largereception volume having a suction duct, a box to be charged with moldingsand mounted so as to be movable into a charging position incommunication with the suction duct of said chamber and in communicationwith the discharge opening of said holder, said communicationsconstituting the only access to the box in said charging position, andmeans for creating in said chamber a comparatively high vacuum to removeabruptly the atmospheric air from the interior of said box into saidchamber thereby causing a quantity of sand to penetrate abruptly andsubstantially free of admixture of air through the discharge opening ofthe holder into the box for filling the latter with compacted sand, saidbox having suction apertures provided at undercut regions of the boxinterior and suction conduits extending in the box walls from saidsuction apertures to at least one central suction station positionedimmediately before a suction nozzle of said suction chamber for abruptlyproducing a pressure drop in the-interior of said box.

f9. A. machine for producing casting blanks, casting cores and castingmolds, said machine comprising a holder for molding sand, said holderbeing open at the top to the atmosphere and having a discharge opening,a suction duct,

a box having a hollow interior space for charging the same with moldingsand and being movable into a charging position in communication withthe discharge opening of said holder and with said suction duct, saidcommunications constituting the only access to the box in said chargingposition, a suction chamber with high air capacity and comparativelylarge air reception volume arranged near said box, said suction chamberbeing in the form of a large suction cylinder having a suction end, saidsuction end being connected to said suction duct, and means for creatingin said suction chamber a comparatively high vacuum and abruptlyairwise, enlarging said interior box space by said air reception volumeto remove abruptly the atmospheric air from the interior space of saidbox into said reception chamber thereby causing a substantiallycompacted quantity of sand to penetrate abruptly and substantially freeof admixture of air through the discharge opening of the holder into thebox filling the latter with compacted sand, said means for creating saidcomparatively high vacuum and abruptly enlarging said interior box spaceincluding a suction piston displaceable in said cylinder from saidsuction end to a limit position.

10. Machine according to claim 4, wherein a partition plate isinterposed between the top and the bottom cylinder, said plate includingducts for supplying pressure air to and discharging from said cylindersto displace said twin piston therein.

11. Machine according to claim 6, characterized by a central controlvalve controlling the supply of compressed air to the quick-acting airvalves of the cylinders.

12. Machine according to claim 7, wherein the air filter means is in theform of a filter layer which is disposed directly in the machine tablebetween said suction nozzle and said suction cylinder of said vacuumpump. 13. Machine according to claim 12, wherein said air filter meansis a wide-surface filter layer of substantially the same diameter as thesuction piston of said vacuum pump.

14. Machine according to claim 12, wherein said filter layer comprises agranular metal swarf.

15. Machine according to claim 12, wherein said air filter meanscomprises a finely perforated capsule releasably fitted into saidmachine table and filled with filter material.

16. Machine according to claim 12, wherein said filter layer is aplate-like ceramic filter member releasably fitted into said machinetable. t

17. Machine according to claim 12, wherein said machine table comprisesa number of stacked plates and one of the plates is fo'rmed with arecess to receive said filter layer. 1

18. Machine according to claim 17, wherein said filter layer is disposedin the bottom plate of the machine table and is retained by the topplate, said top plate including at least one suction nozzle.

19. Machine according to claim 17, wherein said filter layer is disposedin the top plate of the machine table and is retained by means of acover disc, said cover disc including at least one suction nozzle.

20. Machine according to claim 17, wherein the top plate includes spacesforthe passage of a coolant to cool said filter layer and said suctionnozzle.

' 21. Machine according toclaim 20, wherein at least one sealingmean'sis provided around the suction ducts and around said filter layer in thegap between the top plate and the bottom plate of said stack of plates.

22. Machine according to claim 7, wherein an air washer is included insaid suction pipe between said air filter means and said suctioncylinder of said vacuum Pl P- 23:.' Ma'chine according to claim 22,wherein said machine table plate comprises suction ducts which extendfrom said suction nozzle to said air filter means and to said air washerand also to the suction cylinder of said vacuum pump, said machine tableplate also including at least one air removal channel extending fromsaid suction cylinder of said vacuum pump to at least one springloadedair-ejecting non-return valve.

24. Machine according to claim 23, wherein said air filter means isfitted in said plate and said air washer and said non-return valve aresupported by said plate.

25. Machine according to claim 8 in which said box has sealing meansprovided around said suction station and said charging aperture in theouter walls of said box.

References Cited in the file of this patent UNITED STATES PATENTSPeterson June 25, Lougheed Nov. 4, Vest Feb. 25, Mariette Aug. 2, DeRanek Aug. 7, Taccone May 27, Daniel et al. Aug. 7, Magnuson et al. Aug.21, Peterson Sept. 4, Buhrer May 21,

